Channel quality estimation for cooperative demodulation in coded OFDM systems with decode‐and‐forward relays

Abstract

In a cooperative communication system, the destination needs to perform cooperative demodulation, which properly combines the two versions of received signals, one through the source–destination link and the other through the source–relay–destination link. Whereas the quality of the source–relay–destination link can be easily estimated at the destination in an amplify‐and‐forward relay system, the channel quality estimation may be more difficult in a decode‐and‐forward relay system, and inaccurate estimates can severely degrade the system performance. This may be especially true for coded orthogonal frequency division multiplexing relay systems, where each subcarrier may have different channel quality and error correction is performed at the relay. This letter proposes a channel quality estimation method for cooperative demodulation technique in coded orthogonal frequency division multiplexing systems with decode‐and‐forward relays. Copyright © 2013 John Wiley & Sons, Ltd.